Field of the Invention
The invention relates to a transfer printing apparatus and a manufacturing method, and more particularly, to a transfer printing apparatus suitable for light guiding film and a manufacturing method of light guiding film.
Description of Related Art
With rapid progress in display techniques, the flat panel display has become the mainstream among various displays and replaced the cathode ray tube (CRT). Among various flat panel displays, the liquid crystal display (LCD) has been deeply favored by the consumers for usage. Generally, the LCD is mainly formed by a backlight module and a liquid crystal display. Since the LCD does not emit light by itself, it is required that the backlight module provides a light source required for displaying.
In a design trend of making a portable electronic device thinner, a thickness of a light guiding film (LGF) in the backlight module is reduced accordingly to be smaller than a size of the light source (e.g., a LED light source). In order to cover a range where the light source being located with a light incidence side of the light guiding film, a taper is required to be disposed on a light emitting surface of the light guiding film adjacent to the light incidence side, so that light emitted by the light source can enter the light guiding film more completely. Currently, a manufacturing method of the taper is mostly done by injection molding method, however, it is difficult to manufacture a thinner light guiding film and the taper thereof since a minimum thickness of the light guiding film manufactured by the injection molding method is approximate 0.4 to 0.5 mm. Furthermore, in case convex microstructures on the light guiding film are manufactured with a transfer printing method, corresponding transfer printing microstructures are generally engraved on a transfer printing roller directly, such that the transfer printing roller may then be utilized to transfer print the convex microstructures on the light guiding film. Accordingly, when it is required to alter a distribution manner or structure shape of the optical microstructures on the light guiding film, since the transfer printing roller needs to be re-engraved, the manufacturing cost is increased.
Furthermore, in a conventional backlight module, convex (or concave) microstructures are usually disposed on a bottom surface of the light guiding film so that light emitted by the light source can be reflected by the convex (or concave) microstructures to travel towards the light emitting surface after entering the light guiding film, and the convex microstructures are disposed on the light emitting surface of the light guiding film so the light is emitted more uniformly to further improve a luminosity. However, because the convex (or concave) microstructures disposed on the bottom surface of the light guiding film is generally being non-uniformly arranged, when the convex (or concave) microstructures are manufactured on the bottom surface of the light guiding film, a positioning process with the taper on the light emitting surface of light guide film is required, and even slight errors on the positioning may result in a bad influence to the light emitting efficiency. Moreover, in comparison with the convex microstructures being disposed on the light guiding film, generally, a more preferable light emitting efficiency may be obtained by disposing the concave microstructures on the light guiding film. However, in case the concave microstructures are disposed on the bottom surface of the light guiding film so as to obtain the more preferable light emitting efficiency, an issue that the light is emitted non-uniformly may arise due to electrostatic adhesion between the bottom surface of the light guiding film and a reflector.
Taiwan Patent No. TW 201305622 A1 discloses a manufacturing method of transparent substrate, in which a transparent substrate is manufactured into a mold core after the mold core is filled with a material, then the material is cured to form a taper portion on the transparent substrate, and optical microstructures are transfer printed on the transparent substrate through on an inner surface of the mold core. Taiwan Patent No. TW M256280 discloses a light guiding plate mold including an upper mold, a lower mold and a platen, in which the platen is located at the lower mold and has a plurality of microstructure patterns for manufacturing optical microstructures on a surface of the light guiding plate. Taiwan Patent No. TW M446697U1 discloses a manufacturing process of light guiding plate having a stamper rolled by a transport roller, in which when a substrate is delivered by a delivery device to pass a rolling device, the stamper presses a resin layer on the substrate, and an ultraviolet light source emits an ultraviolet light to the resin layer so as to cure the resin layer. Taiwan Patent No. TW 290815 discloses a mold set having a mold core which is capable of being detachably assembled according to variations required for desired shapes and styles. Taiwan Patent No. TW 274255 discloses a punching mechanism capable of forming 3-D textures on a texture mold for desired textures, and forming one single 3-D texture plastic tile by punching patterns with 3-D textures on the texture mold being continuously transported on a leather belt and cutting a resultant of above into a 3-D block by using a knife mold. Taiwan Patent No. TW I249658 discloses a manufacturing method of matrix substrate unit, in which a UV adhesive is coated on a surface of a matrix mold having textures, and a transparent substrate is covered on the UV adhesive; and the UV adhesive is separated from the matrix mold after the UV adhesive is cured, so that the textures of the matrix mold can be completely copied onto the UV adhesive. Taiwan Patent No. TW I346040B1 discloses a manufacturing method of brightening film, in which a modeling adhesive is coated on a release film of a transparent material and released by a releasing wheel of the release film; after being cured by irradiating with a UV light, the modeling adhesive is accommodated together with the release film then cut into a plurality of brightening films. Taiwan Patent No. TW M351374 discloses a manufacturing apparatus of optical film, in which a substrate enters a mirror wheel along a transport direction, and an included angle between the transport direction and a curved line of the mirror wheel proximate to the substrate is 10 to 60 degrees or 30 to 60 degrees. Taiwan Patent No. TW M411335 discloses an embossing machine which presses a pending object by a pressing wheel through a pressing film, and cures a thermosetting collosol layer on the pending object by utilizing a UV light.